It is known that highly efficient combustion of liquid fuel can be realized by providing very fine fuel droplet sizes. The rate at which fuel will burn is a function of its surface to volume ratio which is proportional to the quantity 1/r, where r is the radius of the fuel droplet. Small fuel particle sizes can be obtained using high pressure nozzles which force the fuel through very narrow passages or small orifices. Such devices work quite well at reasonably high fuel flow rates; however, the passages required for low fuel flow rates become so small that they clog easily if there are any solid contaminants in the fuel. These high pressure atomizers may also require the expenditure of substantial power by the fuel pump or the air blower.
Babbington Engineering, Inc. markets a low pressure atomizer. A sketch of this atomizer is shown in FIG. 1. Fuel is introduced at the topmost part of a hollow sphere. The liquid spreads out over the surface as the liquid flows downward forming a film of decreasing thickness as it approaches the equator of the sphere. Air under pressure is introduced into the inside of the sphere through a tube and leaves through a slot located on the equator where the film is a minimum. A portion of the fuel is blown away by the air stream and forms into very small droplets. The remainder of the liquid continues to flow downward and is collected at the bottom and is returned to the system. The Babbington atomizer is sensitive to orientation. The amount of fuel atomized is controlled by changing the air supply pressure which is a limitation on the extent of control. The device requires recirculation which means additional equipment.
What is needed is a better atomizer for use at low flow rates.